Nearly doubling its lead-in (+192%) opposite Fox’s 2011 World Series Game 2, ABC self-starter “Grey’s Anatomy” stood as Thursday’s No. 1 drama in Adults 18-49 for the 5th week runningthis season. Leading its original non-sports competition in the 9 o’clock hour by wide margins, ABC’s “Grey’s” (3.5/9) beat out CBS’ “Person of Interest” by 30% (2.7/7). In addition, the ABC drama dominated its time slot over the World Series across all key Women demos (W18-34/W18-49/W25-54). “Grey’s” qualified as Thursday’s No. 1 TV show overall with Women 18-49 for the 4th time in 5 weeks this season.

Despite facing the World Series, “Grey’s” was up 3% over its week-ago preliminary Adult 18-49 rating (3.4/9 in last week’s the Fast Affiliate ratings). In addition, the ABC drama equaled a best-since-premiere number with Adults 25-54 (4.2/10).

“Private Practice” (10:00-11:00 p.m.)

Building its Adult 18-49 audience for the 2nd week in a row, ABC’s “Private Practice” ran neck-and-neck with “The Mentalist” for the drama lead in the 10 o’clock hour (2.4/6 vs. 2.5/7). Beating “The Mentalist,” “Private Practice” registered as the No. 1 drama in the hour for the 4th straight week with Adults 18-34 and among key Women demos (W18-34/W18-49).

Up against the Fall Classic, “Private Practice” posted its strongest numbers since its season opener across all key Adult demos, growing week to week by 6% in Adults 18-34 (1.7/5 vs. 1.6/5), by 4% in Adults 18-49 (2.4/6 vs. 2.3/6) and by 4% in Adults 25-54 (2.9/7 vs. 2.8/7).

A note about increasing DVR penetration and year-to-year rating comparisons: Year-to-year rating comparisons based on the Live + Same Day data stream are distorted by the level of DVR penetration in the Nielsen sample, which has jumped up to 42% currently, from 38% at the same point in 2010. More viewers are watching shows on their own timetables, which may not be reflected in the overnight next day numbers. The only truly valid year-to-year comparison would be one based on the Live + 7 Day metric, once those stats are released by Nielsen.

Source: The Nielsen Company (Fast Affiliate, Live + Same Day Ratings), 10/20/11.